anachronism

1a person, a custom or an idea that seems old-fashioned and does not belong to the presentThe monarchy is seen by many people as an anachronism in the modern world.She said nuclear weapons were an anachronism in the post cold war era.

2something that is placed, for example in a book or play, in the wrong period of historyThe book is full of anachronisms which suggests there were parts rewritten in later centuries.